1. Field of the Invention
This invention relates to an organopoly-siloxane composition for use in imparting non-tackiness, water repellency, lubricity and wear resistance to rubber surface, and more particularly, to an organopolysiloxane composition for use in surface treatment of rubber to form a durably wear resistance coating thereon. It also relates to a rubber substrate having a coating of the composition.
2. Prior Art
Inert silicone oil and various curable organopolysiloxane compositions have been used for imparting non-tackiness and water repellency to rubber surface.
The inert silicone oil has high initial wear properties, but does not last long since it is readily shed from the substrate surface by physical action as weak as water washing.
The curable organopolysiloxane compositions used heretofore are typically those containing a both end hydroxyl-blocked diorganopolysiloxane, a Si--H group-containing organopolysiloxane and/or an organoalkoxysilane, and an organic tin compound. These compositions form on the substrate surface coatings which are acceptably tack-free and water repellent, but poor in lubricity and wear resistance. It is possible to improve adhesiveness with a substrate, lubricity and wear resistance by adding a mixture or reaction product of an organopolysiloxane having an epoxy group such as glycidoxy group and epoxycyclohexyl group and alkoxysilane or siloxane having an amino group (Japan Kokoku Nos. 54-43023, 56-19813 and 56-47864), but the improvement is not yet fully attained. It is also possible to improve lubricity and wear resistance by adding inert silicone to such organopolysiloxane compositions (Japan Kokoku No. 4-80072), but the coatings are not satisfactorily durably wear resistant where frictional forces are repeatedly applied. There is a strong desire for improving coatings to be durably wear resistant.